With respect to ordinary swing-doors, retractable doors have the advantage of minimizing their space occupation, particularly during opening and closing, when swing-doors must rotate about their hinges, with a wide radius of motion of the door, within a surface that accordingly cannot be rendered useful. This situation affects the opening, the closure and the positioning of doors for walls, as well as the opening, closure and positioning of doors or door wings for pieces of furniture, with consequent problems in terms of space, particularly in apartments, in offices or in any case in small enclosed spaces.
According to a predominant method, such retractable doors, particularly for masonry, have an upper edge which is provided with a pair of brackets with corresponding rollers, which are rendered able to slide on a guide which also continues along a blind compartment which is provided in the wall, on the side where one wishes to push the retractable door. A more solid and complete form or structure of this traditional method is disclosed for example in EP0417000.
In the specific sector of furniture, the retraction of a sliding door wing corresponds normally to its full or partial arrangement behind an adjacent visible door wing, both wings being provided with respective guides or tracks for support and translation and the piece of furniture generally not having a blind and fixed front wall, behind which the wing of the compartment to be opened is pushed so as to be concealed.
In any case, again in the furniture sector, solutions have been proposed which tend to translate the sliding door wing for opening, until it is in a position that is parallel to the side wall of the piece of furniture. One of the first known solutions of this type is constituted by FR 2.690.195. According to the teaching of this patent, a sliding door of a piece of furniture is provided in two vertical elements, both of which are engaged in two front guides, an upper one and a lower one, of the piece of furniture, and are pivoted to an intermediate shoulder, which is not coupled to the guides, and can close by pivoting along one edge onto the shoulder, during the opening of the internal space, in order to be guided and accommodated in a compartment which is lateral with respect to the useful internal space of the piece of furniture.
This solution has indeed solved the problem of eliminating the space occupation of the door when the internal space of the piece of furniture must be opened and must remain open, ensuring minimal space occupation even during the opening and closure of the door. However, the difficulty of supporting the door in a manner that is vertically stable over time, due to its weight which acts on the front and depth guides of the piece of furniture, as well as the delicate nature of the device for rotation at right angles of the door, in order to enter and exit from its retraction compartment, have led to limited use of this solution.
Another known solution is constituted by the teaching of DE 19902918, according to which the sliding door wing is associated laterally and pivoted to an upright which can perform a translational motion in depth on the side or side element of the piece of furniture, the upright being supported by the ends of two bars that are arranged in a pantograph-like arrangement, in which one end can slide along a guide respectively of the upright and of the bottom of the piece of furniture, and being accommodated in the same compartment that accommodates the retracting door.
Even this solution, despite contributing to solve the problem of the space occupation of the door of a piece of furniture, has encountered limited application, mainly because a substantial extent of the compartment is designed to accommodate the supporting pantograph, even in the case of a door in the retracted condition, with the consequent need to be able to provide doors that only have a small aperture or to provide double-wing doors which are mutually hinged along one edge. In this second case, in addition to the less than exciting aesthetic appearance, there is also a considerable cantilever load that acts on the crosspiece, with a rapid deterioration of its supporting guides. However, the greatest drawback of this solution is constituted by the fact that when the crosspiece is in the closed position, therefore with the door in the retracted condition, its supporting capacity is at its minimum, with a heavy imbalance and misalignment of the doors even during the closure of the piece of furniture.
A more recent solution has been disclosed in WO2007/148366, according to which the sliding door of a piece of furniture is constituted by a door with a first door wing which is articulated to a second door wing, which is mounted so that it can slide within the retraction compartment, and is characterized in that the first door wing is guided by guiding elements which are arranged on the upper and lower edge and can slide on an upper and lower guide that lies parallel to the front edge and to the inside of the retraction compartment, and in that the supporting element comprises elastic means which can be subjected to torsion during the closure of the door, transmitting to the supporting element a force which is sufficient to cause a retraction motion of the door wings into the folded position within the retraction compartment.
Even this solution, despite improving the operating conditions of the above cited FR 2690195, is in any case limited by the presence of a door that is provided in three elements and therefore has a poor aesthetic impact. Moreover, this solution entails a considerable constructive complexity, which affects considerably the times and costs of the production and maintenance of cabinets or pieces of furniture of this type.
These and other similar known solutions, furthermore, often do not provide for the possibility of damping the end of the stroke, during the insertion and extraction of the wing from the lateral compartment, in addition to generally providing for a closed condition of the wing that does not cover the uprights of the piece of furniture and therefore has a negative effect on the utilization of its useful internal space.